At three years old, the mangoes yielded about 100 fruits each. Moses Ssentamu, a citrus farmer with over 100 trees in Bamunanika, Luwero district was happy about this.
He projected that if he sold each mango at just sh300, each tree will give him sh30,000 or sh3m from the 100 trees that occupied about a quarter of land. Then, a few weeks after fruiting, the mangoes started rotting!
“I tried so many applications including spraying the trees but the rotting persisted,” Ssentamu says. The disease did not only affect his farm, but also neighbors.
“Fruit flies must not continue attacking and destroying fruits because there are now means to handle them,” says Judith Tukamushaba from Gold Seed International, who deals in the Pheromeno traps that are used to attract and kill the flies. There are also other fly traps that go for as low as sh20,000 each.
The oriental fruit fly originates from Asia and has invaded various parts of Africa, including Uganda and other tropical countries. According to farmers, this fly is a menacingly aggressive invader.
According to scientists, the fly attacks several fruits. These include mangoes, oranges, paw-paws, lemons, grapefruit, bananas, watermelon, plantain, tomato, guava, pepper, avocado, cucumber, pumpkins and many others.
How damage is caused to fruits
Female flies lay eggs on flowers and fruits. Then eggs hatch into larvae that feeds on pulp of the fruit and then the larvae emit the bacteria that cause rotting of fruits. Infested fruits get spoilt quickly and often fall to the ground prior to ripening.
Such is the damage caused by the flies to fruits are so big that none of the fruits can be taken to the market. In many cases, losses are 100%.
How the trap works
The trap uses sex attraction of flies to attract them into a bottle. The pheromones are mixed with insecticide and applied to a suitable medium that may be cotton to allow for slow release of the hormones, that selectively attract and kill the male flies.
Steps for making the traps
- Cotton strips are treated with attractant and an organophosphate. Treatment is done in a vacuum and cotton treated strips covered in air tight containers for 24 hours. You can use mineral water bottles, a bucket or a jerrycan that is clean. Two small holes opposite each other are made on the container.
- Using a nail, holes are made on bottom of container to allow water get out in case it rains. The treated strip is picked and suspended in a container using a copper wire or string. Suspension of the strip is above the openings to avoid wind blowing the strip. The trap is suspended on a tree branch. One acre of around 400 trees will require 15 traps.